Definition of jackanapes in English:

noun

I was at school with a Bruno, and as the grinning jackanapes sat at his piano and segued effortlessly from Bach to the Beatles and back again via Satie, nobody queued up to congratulate him; they simply wanted to beat him up.

The grinning jackanapes in Number 10 must not be allowed to extinguish Britain's liberties: he and the Great Uncleanness that is New Labour must be evicted from power.

The grinning jackanapes who has so arbitrarily dismantled the constitution is now half mad with power.

In the reign of Queen Elizabeth, one Peter Palmer, of Lincoln's Inn, brought an action against a barrister of the name of Boyer, for having, with the intention to injure him in his name and practice, said, 'Peter Palmer is a paltry lawyer, and hath as much law as a jackanapes.'

Origin

Early 16th century (originally as Jack Napes): perhaps from a playful name for a tame ape, the initial n- by elision of an ape (compare with newt), and the final -s as in surnames such as Hobbes: hence applied to a person whose behavior resembled that of an ape.